Study On Treatment Of Dye Wastewater Based On Three-dimensional Electrode Fenton Process

Dyes from the aromatic compounds,aniline,phenol,etc.as raw materials by nitrification,iodide production of intermediates,and then diazotization,coupling and sulfuration reaction synthesis.Due to the variety of dyes and intermediates,the composition and properties of dye wastewater are different.Dye wastewater has high chroma,poor biodegradability,and high content of organic pollutants.As a result,the chemical oxygen demand(COD)of dye wastewater can reach tens or even 100,000 mg per liter of water.Electron Fenton method synthesizes Fenton reagent in the electrolyte by electrochemical action.It is widely used in the field of dye wastewater because of its short reaction time and good treatment effect.Three-dimensional electrode refers to a particle material with catalytic activity,conductivity,and adsorption capacity.Under the action of an electric field,a microelectrode formed by a difference in surface potential is generated.In this study,the dye wastewater from a Zhejiang Chemical Co.,Ltd.was treated as the object of treatment.The parameters affecting the two-dimensional electrode-electric Fenton method and the three-dimensional electrode-electric Fenton method were investigated and the optimal conditions were investigated.The two-dimensional electrode-electric Fenton method and the three-dimensional electrode were compared.The removal efficiency of the electro-Fenton method was analyzed and the three-dimensional electrode-electric Fenton mechanism was analyzed.The study found that:using graphite electrode plates,the electrolysis time is 2h,the current density is1.2A/mm~2,the plate spacing is 2.5cm,the concentration of ferrous sulfate is 0.5g/L,pH=2.5,and the aeration volume is 2L/min,the stirring speed of 1000 r/min,the dye COD removal rate was27.84%.The effect of COD removal rate on the significance of the parameters from big to small was:pH,dosing of ferrous sulfate,current density,plate spacing.The influencing parameters of three-dimensional electrode-electron Fenton electrode material,pH value,current density,plate spacing,dosing amount of ferrous sulfate,particle electrode type,and dosage were studied.The results showed that:The tantalum-plated titanium electrode was used as the anode,stainless steel as the cathode,and the powdered activated carbon(PAC)as the particle electrode.The pH was 2,the current density was 1 A/mm~2,the distance between the plates was 3cm,and the ferrous sulfate was cast.The best removal rates of COD,TOC,color,and ammonia nitrogen were 62.8%,41.15%,95%,and 42.48%,respectively,for the 0.5 g/L addition and 2.0 g/L powdered activated carbon.Better than two-dimensional electrode-electric Fenton method.The proportion of the removal of each oxidation mechanism in the system from the high to the bottom was:PAC adsorption,hydroxyl radical oxidation,hypochlorite oxidation,and plate direct oxidation.Through RSM optimization analysis,the influence degree of the parameters of the removal efficiency of the three-dimensional electrode-electric Fenton method is ranked from the largest to the smallest:PAC dosage,plate spacing,pH,current density and ferrous sulfate dosage,current density and other influences The parameters have interactions and the stainless steel cathode material limits the removal efficiency of the system.PAC acts as a particle electrode with adsorption and catalysis.Under the optimal conditions,the treatment efficiency of PAC three-dimensional electrode system was studied.The results showed that the COD removal efficiency of dye wastewater was increased by 18%compared with saturated adsorption PAC and the new PAC as particle electrode.When the three-dimensional electrode system was de-energized for a period of time,the new PAC and saturated PAC were used as the particle electrode,and the COD value of the dye wastewater was increased.At 10%,it was shown that the electric field increased the PAC adsorption efficiency by 10%.The PAC particle electrode was subjected to a cyclic reuse experiment.As the number of recycling cycles increased,PAC gradually reached an adsorption saturation state,which was consistent with the effect of saturated PAC as a particle electrode.After cycling 7 times,the two are basically the same,and the electric field promotes the adsorption of PAC by 2%to 3%.